The present invention is related to a method for forging/molding a coarse blank of an oil cylinder. According to this method, burn-in softened aluminum material is first forged and molded into a blank body of the oil cylinder and then the blank body is continuously secondarily forged and molded into a coarse blank of the oil cylinder.
FIG. 7 shows a general oil cylinder 9 including a cylinder body 91 and two end caps 92, 93 disposed at two ends of the cylinder body 91. The two end caps 92, 93 are respectively formed with oil inlet 921 and oil outlet 931. A piston rod 94 passes through at least one end cap. The two end caps are serially connected by four bolts 95 to form the oil cylinder. The end caps are mostly square and apparently protrude from the circumference of the cylinder body. conventionally, the end caps and the cylinder body are separately manufactured and then the end caps are connected with two ends of the cylinder body by means of welding or screws. Such manufacturing procedure has poor efficiency. Moreover, in the case that the end caps are not truly connected with the cylinder body, the oil will leak from the oil cylinder. Besides, the four bolts must have a length in accordance with the length between the end caps so that the cost is higher. In order to fixedly mount the oil cylinder in a predetermined position, one of the end caps is formed with a lug for a screw or a pivot shaft to pass therethrough.